Where do we start when talking about Bears?

If the Bears’ miserable performance Saturday against the Bills at Soldier Field was a hint of what’s coming, head for the hills.

Try Costa Rica. Or New Zealand. Have a cool drink. Forget football. Come back next spring and enjoy a fresh Bears ‘‘rebuild.’’

If that 41-15 thrashing meant anything, you almost can write the script for 2021: Veteran Andy Dalton will get benched, young Justin Fields will start and eventually get demolished (see ominous blindside hit from Bills linebacker Andre Smith, for example), the Bears’ defense will implode, assistant coaches will get fired, fans will boo and possibly wear bags on their heads and chairman George McCaskey will say ‘‘Mama Bear’’ Virginia McCaskey is ‘‘pissed off.’’ Again.

You know the drill. You’ve seen it before.

Big expectations turn into little results.

It’s hard to say what was most dispiriting about the game, in which the Bears fell behind 28-0 in the first half.

It might have been Dalton’s first few three-and-outs.

It might have been the much-lauded Bears defense seeming to prefer bumper cars to tackling.

It might have been the running game, which barely crawled.

It might have been the coaching, from head man Matt Nagy down to whoever is supposed to teach Fields how to buckle his chinstraps tightly.

It might have been — and I shudder even to suggest such lunacy — overconfidence by the Bears, for reasons that must escape any sane human being.

But whatever the malaise was, it was perhaps best captured by the sparkling performance of visiting Bills quarterback Mitch Trubisky, who returned to Chicago for the first time since being all but run out of town on a donkey in the spring.

Trubisky passed for 221 yards and led four touchdown drives for the Bills — in the first half. And he did much of it against the Bears’ alleged first-string defense.

And he’s not even the Bills’ starting quarterback!

Something was so wrong here that it was nearly philosophical, like a new postulate that expands in circles until it smacks you in the face.

What if Bears general manager Ryan Pace didn’t merely mess up one or two quarterback choices (i.e., drafting Trubisky so high in 2017, signing Dalton as a starter this year) or even made a third bad choice (trading for Nick Foles as a supposed starter in 2020)?

What if he also screwed up by dumping Trubisky precisely when he was blooming?

What if — true horror — simply being a Bears quarterback means doom? What if Nagy doesn’t know how to get the full potential from a quarterback, any quarterback?

OK, it was only a preseason game. And it has been said over and over that they’re just dressed-up practices. The Bears’ offensive line was a patchwork thing, and lots of starters were out. All that matters is the regular season, with healthy players. These sideshows don’t mean much, etc.

And maybe Trubisky was all fired up in revenge mode. Still, he had nothing but nice things to say before and after the game, including, ‘‘I love the people of Chicago.’’

Yet it was Nagy himself who said the obvious: ‘‘There was more that wasn’t good than good.’’

Of the blast from Smith that sent his helmet flying — thank God, without his head in it — Fields said: ‘‘Hey, man, I learned from that.’’

Brother, we hope so. You’re supposed to learn in the preseason. And as former Bears quarterback Jay Cutler used to say with annoying frequency about mistakes, you ‘‘clean it up’’ and move on.

You just wonder whether the Bears’ problems are able to be cleaned up.

A quarterback can’t solve all a team’s problems. The defense has to stop somebody.

Fields has great potential. His running ability and pure speed give him an edge that can’t be taught. But as dynamic as he looked in the first preseason game against the Dolphins, he seemed to come back to earth Saturday.

Losing by 26 points at home isn’t good for morale under any circumstance. The hope is the Bears were embarrassed and come out with new drive from here on.

Trubisky shocked us with his excellence. But bad play at this stage isn’t fatal, either. Consider that so far this preseason, the Chiefs’ Patrick Mahomes has completed only 55% of his passes for 82 yards, no touchdowns, an interception and a 44.2 passer rating.

And he’s all-world.

Right now in Chicago, we’d take the Bears just being all-Illinois.